The Swedish utility company Roslagsvatten recently announced they will build a new wastewater treatment plant in Margretelund near Stockholm together with NCC. The work will be carried out as a turnkey contract and the order value will be approximately SEK 1.2bn.
The new wastewater treatment plant in Margretelund, Roslagsvatten’s largest project ever, will be one of Sweden’s most sustainable wastewater treatment plants. The wastewater treatment plant will be built “with respect for people and the environment, with technology to face the future and based on Roslagen’s nature, culture and history”.
“Since 2018, Roslagsvatten has been investigating different alternatives to ensure future wastewater treatment for Österåker and Vaxholm Municipality. This is a big step forward for Roslagsvatten, and there is a lot of work behind the decisions. The new wastewater treatment plant, which will meet wastewater treatment needs for decades to come, ticks off all the requirements we have regarding environmental considerations, economy and technology”, says Christian Wiklund, CEO of Roslagsvatten.
AquaGreen’s technology supports Roslagsvatten’s stringent requirements for sustainability and circularity
The investment in biochar and a state-of-the-art steam drying and pyrolysis plant is an important piece of the puzzle at the new wastewater treatment plant. AquaGreen is a Danish greentech company that has developed a unique integrated steam drying and pyrolysis process together with the Technical University of Denmark (DTU). It is this technology that has been chosen for the sludge treatment part of the new treatment plant. Among other things, through the choice of biochar production as part of the solution, the investment will contribute to eleven of the UN’s Sustainable Development Goals.
The process consists of two steps: 1) drying of dewatered sludge for 2 hours at 200 °C and 2) pyrolysis of dried sludge for 20 minutes at 650 °C. Everything takes place in an oxygen-free environment and the entire process is fully integrated and closed, eliminating problems with odours and dust.
“The fact, that we cooperate with AquaGreen as a supplier of steam drying and pyrolysis plants, will lead to a significantly stronger fulfilment of our vision, and our requirements for climate and environmentally friendly resource utilization, than with other technical solutions. The final product, the biochar, is odourless, dry and of very high quality (free from micropollutants). The biochar is fully hygienized and at the same time contains 5-6% phosphorus, which enables direct use of the biochar on agricultural land as fertilizer (which will also significantly reduce our climate footprint)”, says Aleksandra Lazic, project manager and development engineer at Roslagsvatten.
The collaboration is also praised by AquaGreen:
“Roslagsvatten initially commissioned a preliminary project, which was delivered in August 2022. The preliminary project showed that the pyrolysis process will reduce sludge transports from the treatment plant by 90% because the amount of sludge will be reduced accordingly. We are proud of and look forward to the cooperation. This will be a milestone in the Swedish market, and we have already noticed a great interest in pyrolysis plants and biochar from many Swedish utilities”, says Henning Schmidt-Petersen, CEO of AquaGreen.
AquaGreen is a Danish greentech company dedicated to addressing environmentally harmful substances and climate change through innovative solutions for sustainable biomass treatment. The company’s groundbreaking technology destroys organic pollutants such as PFAS, produces renewable energy, recirculates nutrients and stores CO₂ in biochar, creating a significant positive impact on the environment and climate.
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